The present invention relates to bag making machines, and more particularly to a method and apparatus for imparting an identifying code to each bag made by the machine.
Certain bags, such as plastic bags and the like, are made at the rate of hundreds per minute on a bag making machine which has a plurality of identical bag making stations. Each station of the machine produces a bag, so it is important to be able to identify a station which is producing a defective bag. Accordingly, it is the principle object of the present invention to provide a system for coding each bag so that, by inspection of the bag, the station at which it was made can be readily identified. Moreover, it is an object to provide such a system wherein the code imparted to the bag does not detract from the appearance of the bag, and preferably, is obvious only to a trained eye.
The present invention is particularly useful in rotary bag making machines, wherein a plurality of bag making work stations are arranged about the periphery of a rotating drum. In such apparatus, a clamp means is provided which tracks the rotation of the drum and holds the bag material to the surface of the drum while the bag making operations are performed. Breakdowns or machine failures of either the clamping means or of a work station, is reflected in a defective bag. It is equally important, therefore, to identify not only the work station at which the defective bag is made, but also to identify the particular clamp means associated with that work station at the time the bag is made. Accordingly, another object of the present invention is to provide an encoding system which codes each bag with identifying indicia representative of both the work station at which the bag is made and the clamp means associated with that work station when the bag is made.